.box-shadow-outset{
    width: 300px;
    height: 100px;
    background-color: red;
    box-shadow: 10px -10px 5px #888;
}

.box-shadow-inset{
    width: 300px;
    height: 100px;
    background-color: aqua;
    box-shadow: inset 10px 10px 10px #888;
}